US President Barack Obama has started an extraordinary visit to Cuba, eager to push decades of acrimony deeper into the past and forge irreversible ties with America's former adversary.
Mr Obama's whirlwind trip is a crowning moment in his and Cuban President Raul Castro's effort to restore normal relations between their countries.
While deep differences persist, the economic and political relationship has changed rapidly in the 15 months since the leaders vowed a new beginning.
Wielding an umbrella on a rainy Havana afternoon, Mr Obama and his family stepped off Air Force One and were greeted by senior Cuban officials - but not Mr Castro.
The Cuban leader frequently greets major world figures at Jose Marti International Airport, but he was absent on the tarmac.
Instead, he plans to greet Mr Obama at the Palace of the Revolution.
Mr Obama's national security team said it was "never contemplated or discussed" that Mr Castro would be at the airport, adding that the Cubans consider the palace ceremony as the official welcome event.
"This is a historic visit," Mr Obama said as he greeted US embassy staff and their families at a Havana hotel. "It's an historic opportunity to engage with the Cuban people."
Joined by wife Michelle and his two daughters, he toured Old Havana by foot, walking gingerly on the slippery wet stones in front of Havana Cathedral. A few hundred people in the square erupted in applause and shouted his name as the family stepped forward.
Approaching the Plaza de Armas, a leafy square in a tenderly restored corner of Old Havana, the Obamas were greeted by buoyant chants of "USA, USA".
For more than 50 years, Cuba was an unimaginable destination for a US president, as well as most American citizens. The US severed diplomatic relations with Cuba in 1961 after Fidel Castro's revolution sparked fears of communism spreading to the Western Hemisphere. Domestic politics in both countries contributed to the continued estrangement well after the Cold War ended.
Ahead of Mr Obama's arrival, counter-protesters and police broke up an anti-government demonstration by the Ladies in White group, whose members were taken into custody by female police officers in a scene that plays out in Havana each Sunday.
They are typically detained briefly and then released.
Mr Obama's visit was highly anticipated in Cuba, where workers cleaned up the streets in Old Havana and gave buildings a fresh coat of paint.
American flags were raised alongside the Cuban colours in parts of the capital, an improbable image for those who have lived through half a century of bitterness between the two countries.
But many Cubans stayed home to avoid extensive closures of main boulevards.